Means for disarming a mine



3, 1 .1. F. TOOMEY 2,966,854

MEANS FOR DISARMING A MINE Filed Feb. 12, 1945 AAAAAAAAAAAAAAAAA Zjrwamkm WQL L L awn M1 United States Patent MEANS FOR DISARMING A MINE John F. Toomey, Floral Park, N. (On Top 0 The Hill, Chilmark, Mass.)

Filed Feb. 12, 1945, Ser. No. 577,400

12 Claims. (Cl. 102-18) (Granted under Title 35, US. Code (1952), see. 266) This invent-ion rel-ates to means for disarming a mine for a predetermined period of time in response to a countermine shock or impulse received through the surrounding water and, more particularly, to an inertia controlled anticountermine circuit arrangement in which a relay is operated in response to the closure of a pair of inertia controlled contacts as the countermine shock is received and remains operated for a predetermined period of time thereafter thereby to disable the firing mechanism until the relay releases.

Various devices and arrangements have heretofore been employed to prevent the premature explosion of a mine as a result of a countermine shock received through the surrounding Water, such devices comprising pendulums and inertia controlled elements adapted to be moved from an initial position by a shock or impulse. In the case of pendulum devices, for example, it is, of course, necessary to support the pendulum structure in a predetermined position by means of a gimbal or similar device whereby a pair of pendulum controlled contacts are adapted to be actuated to circuit closing or circuit opening position, as the case may be, when a sudden shock or wave of pressure is received. In the case of the inertia controlled switch devices heretofore employed for disarming a mine in response to a counterm-ine explosion or shock, the devices in general are not entirely satisfactory under all conditions of service for the reason that a considerable amount of mechanical energy is required to operate the devices sufliciently to disarm the mine.

One of the objects of the present invention is the provision of a new and improved disarming mechanism for a mine in which the mine firing circuit is disabled for a predetermined period of time in response to an anticountermine shock of relatively short duration.

Another of the objects is the provision of a mine disarming mechanism in which new and improved means are employed for maintaining the mine disarmed for a predetermined period of time after a shock has been received thereby.

Another object is the provision of a new and improved arrangement for disarming a mine in response to an anticountermine shock in which the disarming mechanism is unresponsive to additional shocks received through the water until a predetermined period of time has elapsed after the first shock is received.

A further object is to provide a new and improved anticountermine mechanism of the character disclosed which is economical to manufacture, reliable in operation and which possesses all the qualities of ruggedness and durability in service.

Still other objects and advantages will be apparent from the following description taken in connection with the accompanying drawing on which is shown as a single figure a complete system and mechanism for firing a mine and for disabling the mine for a predetermined period of time as an anticountermine shock is received through the water.

Referring now specifically to the drawing on which is Patented Jan. 3, 1961 "ice shown in diagrammatic form a complete mine firing circuit and the disarming means therefor according to a preferred form of the invention, there is shown thereon means including a firing circuit for firing the mine in response to a variation in the magnetic field adjacent thereto detected by suitable detecting means, the field detecting means comprising a search coil 10- arranged about a core 11 composed of magnetic material suitable for the purpose such, for example, as a material known in the art as Permalloy, and a sensitive firing relay D connected thereto as by the pair of conductors 12 and adapted to be operated by the electromotive force generated in the coil 10 as the magnetic field adjacent thereto is changed. The relay D is preferably of a type in which a movable contact element 13 is moved into engagement with contact 14 or 15, as the case may be, selectively in accordance with the polarity of the electromotivc force generated by the coil 10, the contact element 13 of the relay remaining in the operated position by reason of the provision of a permanent magnet 16 and a small magnetic mass 17 secured to the movable element 13 and adapted to be attracted by the magnet 16 sufficiently to maintain the element 13 in circuit closing position until the element is forcibly restored by a restore magnet RS.

There is also provided an inertia con-trolled switching mechanism shown in diagrammatic form on the drawing and indicated generally by the numeral 18, the mechanism comprising an inertia member l9 slideably arranged within a support 21 and adapted to close a pair of contacts 22 in response to a shock or wave of pressure received by the casing 23 of the mine to which the support 21 is secured. The inertia switch mechanism 18 may be of any type suitable for the purpose such, for example, as the inertia switch disclosed and claimed in the copending application of S. W. Booth, for inertia Switch And Means Controlled Thereby, Serial No. 484,854, filed April 28, 1943. The inertial switch mechanism is adapted to close a circuit to winding 1 of the disarming relay R whereby current from the normally charged condenser C is caused to flow through a discharge circuit including armature 24 and break contact of relay R as the contacts 22 of the inertia switch mechanism are closed. The winding 1 of relay D is of relatively low resistance, a winding having a resistance of .5 ohm having been found to be satisfactory for the purpose when employed with a condenser having a capacity of the order of 500 microfarads. Relay R is also provided with a holding winding 2 connected at one end thereof to one end of winding 1 and to one terminal of the condenser C. The other end of winding 2 is connected by way of contacts 25 of a hydrostatically controlled arming clock 26 to the positive terminal of battery BA. The resistance of winding 2 is relatively high thereby to delay the charging of condenser C and maintain relay R operated for a predetermined period of time corresponding to the time required for the condenser to charge to substantially a fully charged condition.

The arming clock may be of any type suitable for the purpose such, for example, as the arming clock disclosed in the copending application of James B. Glennon et al. for Firing Mechanism for a Submarine Mine, Serial No. 395,230, filed May 26, 1941, now Patent No. 2,905,088, in which a shaft, such as the shaft 27 is set into operation by a spring driven escapement mechanism in re sponse to the pressure of the surrounding water against the hydrostat element 28. There is also arranged on the shaft 27 and fixed thereto a cam member 29 having a plurality of lobes 31, 32 and 33 thereon adapted to close contacts 25, 34 and 35 respectively in the order named as the member 29 moves through a fractional portion of a rotation thereof controlled by the stop pin 36 and arcuate slot 37 arranged within the member 29 within which the stop pin is disposed. The contacts 25 are adapted to be closed at the expiration of a suitable period of time after the mine has been launched such, for example, as a period of 25 minutes and to remain closed for the life of the mine. The contacts 34 are adapted to be momentarily closed when a relatively short period of time has elapsed after contacts 25 are closed such, for example, as minutes and contacts 35 are closed by the cam element 29 shortly after the contacts 34 have been disengaged and remain closed throughout the life of the mine.

As the movable contact element 13 of relay D moves to circuit closing position, an electroresponsive detonating device 38 is connected to the break contact of relay R and, in the event that relay R is unoperated, negative battery is applied to the detonating device thereby causing the mine to fire.

From the foregoing, it Will be apparent that the operation of relay R interrupts the circuit from the negative terminal of battery BA to the detonating device 38 and thereby prevents the operation of the detonating device as the contact element 13 of relay D is moved to circuit closing position in response to a shock or impulse received through the surrounding water. As armature 24 moves into engagement with the make contact of relay R, negative battery is applied to the restore magnet RS thereby forcibly resetting the movable contact element 13 of relay D to an initial position intermediate contacts 14 and 15 and disengaged therefrom. The restraint is not removed from the movable contact element 13 until relay R releases at the end of a predetermined interval of time sufiicient for the shock or impulse to subside whereby relay D is not actuated to circuit closing position by the shock or impulse.

The operation of the system will best be understood by consideration of a specific example. Let it be assumed, by way of example, that the mine is planted within a body of water of depth sufiicient for the hydrostatic device 28 to set the arming clock 26 in operation and that the shock which the mine received during the planting operation is sufficient to move the element 13 of relay D to circuit closing position.

At the expiration of a period of minutes, contacts 25 are closed by lobe 31 of the cam member 29 thereby applying positive battery to one end of the winding of the reset magnet RS of relay D, to one of the contacts of the arming clock, and to one end of winding 2 of relay R. Condenser C is now charged to the potential of battery BA. The closure of contacts 34 at the expiration of a period of time of 35 minutes closes a circuit from positive terminal of battery BA by way of conductor 39, contacts 25 of the arming clock, conductor 41, winding of the reset magnet RS, conductor 42, contacts 34 of the arming clock, and thence by way of conductor 43 to the negative terminal of battery BA thereby operating the reset magnet RS and restoring the movable contact element 13 of relay D to an initial position intermediate the contacts 14 and 15 and disengaged therefrom. As the lobe 32 of the cam 29 moves away from the contacts 34, the contacts are opened and the reset magnet RS releases thereby removing the restraint from the movable contact element 13 and rendering relay D responsive to signals received from the search coil 10.

Shortly after the contacts 34 are disengaged, the cam actuated contacts 35 are closed by lobe 33 of the cam member 29 and remain closed for the life of the mine. As contacts 35 are closed, positive battery is applied by way of conductor 44 to one terminal of the electroresponsive detonator 38. The detonator is not fired at this time, however, for the reason that the movable contact element 13 of relay D is disengaged from contacts 14 and 15. The mine is now armed.

Let it now be assumed that a countermine shock or wave of pressure is received through the surrounding water of sufficient strength to cause contacts 22 of the inertia controlled switching mechanism 18 to be closed. When this occurs, condenser C is discharged through winding 1 of relay R thereby causing winding 1 to be energized and relay R to be operated quickly over the following circuit: positive plate P of condenser C, conductor 45, winding 1 of relay R, conductor 46, contacts 22 of the inertia controlled device 18, conductor 47, break contact and armature 24 of relay R and thence by way of conductor 43 to the negative plate N of condenser C. Winding 1 of relay R, it will be recalled, is of low resistance and the discharge current flowing through winding 1, therefore, is relatively large. The condenser discharges at a rapid rate and is substantially discharged as relay R operates. As armature 24 of relay R moves away from the break contact of the relay, the discharge circuit of condenser C is interrupted and the condenser charges over the following circuit: positive terminal of battery BA, conductor 39, contacts 25 of the arming clock, conductor 41, winding 2 of relay R, conductor 45, plate P of condenser C from whence the circuit is continued by Way of plate N of the condenser and conductor 43 to the negative terminal of battery BA.

The charging current for condenser C flowing through winding 2 of relay R causes relay R to remain operated until the condenser is substantially fully charged. The resistance of winding 2, it will be recalled, is relatively high whereby the charging current for the condenser C is low and thus a considerable period of time elapses before the condenser is charged sufiiciently for relay R to release, this period of time being of greater duration than the time required for the several shocks or waves of pressure set up by a countermine explosion within the vicinity of the mine to move past the mine.

As armature 24 of relay R moves away from the break contact of the relay, negative battery is removed from contacts 14 and 15 of relay D thereby disabling the firing circuit for the detonator 38 and disarming the mine for a predetermined period of time.

As armature 24 of relay R moves into engagement with the make contact of the relay a circuit is closed from the positive terminal of battery BA by way of conductor 39, contacts 25 of the arming clock, conductor 41, reset magnet RS of relay D, conductor 42, make contact and armature 24 of relay R, conductor 43 and thence to the negative terminal of battery BA thereby causing reset magnet RS to operate and quickly restore the movable element 13 to an initial neutral position intermediate the contacts 14 and 15 and disengaged therefrom before the movable element 13 has been moved by the countermine shock into circuit closing position.

By providing an arrangement in which relay R is maintained operated until sutficient time has elapsed for all of the waves of pressure or shocks from a countermine explosion within the water to move past the mine, movable contact element 13 of relay D is forcibly maintained in an initial neutral position during the time the countermine shocks are received and thus there is no possibility of prematurely firing the mine as the result of a countermine shock. Furthermore, the time during which relay R remains operated is predetermined and fixed regardless of the countermine shocks received by the inertia device 18 during this period for the reason that the circuit to the inertia device is interrupted at the break contact of the relay during the entire period of time the relay is operated.

When condenser C has charged sufficiently for relay R to release, armature 24 moves away from the make contact and interrupts the circuit to the reset magnet RS of relay D thereby removing the restraint from the movable contact element 13 and rendering relay D in a condition to be operated by a signal received from the search coil 10. As armature 24 of relay R moves into engagement with the break contact of the relay negative battery is again applied to contacts 14 and 15 of relay D and the firing circuit is again made effective to operate the detonator 38 in the event that the movable contact element 13 of relay D is moved into engagement with contacts 14 or 15 in response to a signal received from the search coil 10.

Let it now be assumed that the magnetic field adjacent the search coil is changed by a vessel moving above the mine thereby generating an electromotive force within the search coil 10 sufficient to cause relay D to operate. When this occurs, the firing circuit is closed from the positive terminal of battery BA by way of conductor 39, contacts 25 of the arming clock, conductor 41, contacts 35 of the arming clock, conductor 44 to the detonating device 38, from whence the circuit is continued by way of conductor 48, armature 13 and contact 14 or 15 of relay D, as the case may be, conductor 47, break contact and armature 24 of relay R, conductor 43 and thence to the negative terminal of battery BA thereby operating the detonator 38 and firing the mine.

Whereas, the invention has been described with reference to an arrangement for disarming a mine for a predetermined period of time in response to a countermine shock or impulse received through the surrounding water, it will be understood that this is for illustrative purposes only and that the invention in its broader aspects discloses new and improved means for controlling a switching device whereby the switching element there of is maintained continuously operated for a predeten mined period of time in response to an electrical impulse applied thereto and is unresponsive to additional impulses applied thereto during said predetermined period of time.

While the invention has been described with reference to an example which gives satisfactory results, it will be understood by those skilled in the art to which the invention pertains, after understanding the invention, that various changes and modifications may be made without departing from the spirit and scope of the invention and it is my intention, therefore, in the appended claims to cover all such changes and modifications.

The invention herein described and claimed may be manufactured and used by or for the Government of the United States of America for governmental purposes without payment of any royalties thereon or therefor.

What is claimed as new and desired to be secured by Letters Patent of the United States is:

1. In a disarming mechanism for amine, in combination, a mine firing circuit, a relay having a pair of normally closed contacts included within the firing circuit, said relay having an operating winding and a hold winding, a normally charged condenser connected to said windings, a virbationally responsive device secured to said mine and adapted to close a pair of normally open contact elements as vibrations are received thereby, a discharge circuit for said condenser including said operating winding, said normally open contact elements and the normally closed contacts of said relay whereby the relay is operated as the contact elements are engaged, and means including said hold winding and effective after said normally closed contacts have been disengaged for charging said condenser and for maintaining the relay operated until said condenser has received a predetermined charge.

2. In an apparatus of the character disclosed for disarming a mine in response to vibrations received thereby, the combination of, means responsive to a change in the magnetic field adjacent the mine for generating an electromotive force, a sensitive relay connected to said detecting means and having a contact element adapted to be moved from an initial open circuit position to circuit closing position in response to said electromotive force, an electroresponsive detonating device, a firing circuit including said electroresponsive device and adapted to be closed by said contact element as the contact element moves to circuit closing position, electrically controlled means on said relay for forcibly restoring said contact element to said initial open circuit position, a

control relay having an operating winding and a hold winding, a normally charged condenser connected to the windings of said control relay, an inertia controlled switch connected to said operating winding and adapted to close a discharge path for said condenser as the inertia switch operates thereby to operate said control relay, a pair of normally closed contacts on the control relay included within said discharge path and adapted to interrupt the discharge path and thereby deenergize said operating winding as the control relay operates, means including said hold winding for charging said condenser and for maintaining the control relay operated until the charge on said condenser has increased to a predeter' mined value, and means on said control relay in electrical connection with said restoring means for forcibly restoring the contact element of said sensitive relay to said initial open circuit position as the control relay operates whereby the contact element is prevented from being moved from the initial position until said control relay is released.

3. A disarming mechanism for a mine comprising a normally open inertia controlled switch, a relay having a low resistance operating winding and a high resistance hold winding, a normally charged condenser connected to said windings, a discharge path for said condenser including said operating winding and the inertia switch, means on said relay for interrupting said discharge path as the relay operates in response to the closure of said inertia switch, means including a plurality of circuit connections for charging said condenser and for causing the relay to remain operated by the charging current for said condenser flowing through said hold winding until the condenser has charged to a predetermined value, and a firing circuit adapted to be interrupted by said relay interrupting means.

4. In an electrically fired mine of the character disclosed, the combination of, a firing relay, means responsive to the magnetic field of a vessel for operating said relay, normally open contact means on said relay and adapted to be closed as the relay operates, a firing circuit connected to said contact means and adapted to be closed thereby, an anti-countermine switch having a pair of normally open contact elements adapted to be closed and opened repeatedly in response to impulses of pressure received thereby, a firing control relay having a low resistance operating winding and a hold winding, a normally charged condenser connected to said windings, a discharge path for said condenser including said operating winding and said contact elements whereby the control relay is operated by the condenser discharge current as the contact elements are closed, means on said relay for interrupting said discharge path as the relay operates, and means including said hold winding for charging said condenser and for maintaining the control relay operated until the condenser has been charged to a predetermined value whereby the anti-countermine switch is ineffective for a predetermined period of time after the control relay operates.

5. In a disarming mechanism for a mine, in combination, a mine firing circuit, a relay having a pair of normally closed contacts included within the firing circuit, a normally charged condenser connected to a winding of said relay and adapted to operate the relay as the condenser is discharged, means including a vibrationally responsive device adapted to discharge the condenser in response to impulses received through the surrounding water, and means including a second winding on said relay for charging said condenser and for preventing the release of the relay until the condenser is charged to a predetermined value.

6. In an apparatus of the character disclosed for disarming a mine in response to vibrations received through the surrounding water, the combination of, a normally charged condenser, a control relay connected to said condenser and adapted to be operated by the discharge current thereof, a normally open discharge path for said condenser, an inertia switch adapted to close said discharge path as vibrations are received through the surrounding water, means on said relay for interrupting said discharge path as the relay operates, and means including a high resistance winding on said relay for charging said condenser and adapted to be energized by the charging current of the condenser as said discharge path is interrupted for preventing the release of the relay until the condenser is charged to a predetermined value.

7. In an electrically fired mine of the character disclosed, the combination of, a firing relay, means responsive to the magnetic field of a vessel for operating said relay, normally open contact means on said relay and adapted to be closed as the relay operates, a firing circuit connected to said contact means and adapted to be closed thereby, a control relay having a pair of normally closed contacts included within the said firing circuit, a normally charged condenser connected to said control relay and adapted to operate the control relay as the condenser is discharged, an anti-countermine switch having a pair of contact elements adapted to discharge said condenser in response to impulses of pressure received through the surrounding water, means including a plurality of circuit connections for interrupting the discharge of said condenser as the control relay operates, electroresponsive means for restoring the contact means on said firing relay to an open condition, means on said control relay for operating said electroresponsive means as the control relay operates, and means including'a high resistance winding on said control relay for charging said condenser and for maintaining the control relay operated until the condenser is substantially fully charged, whereby the contact means on the firing relay are maintained in an open condition for a predetermined period of time after the anti-countermine switch contacts are closed,

8. In a disarming mechanism for a mine, the combination of, a firing circuit, a control relay for interrupting said firing circuit as the relay operates, a normally charged condenser connected to said relay and adapted to operate the relay as the condenser is discharged, a discharge path for said condenser, vibrationally responsive means for closing said discharge path, means on said relay for interrupting said discharge path as the relay operates, said last named means being adapted to prevent the closing of said discharge path until the relay has released, and means including a high resistance winding on said relay for charging said condenser at a relatively slow rate while said discharge path is interrupted thereby to maintain the relay operated for a predetermined period of time.

9. In a disarming mechanism for a mine, the combination of, a mine firing circuit, a relay having means adapted to interrupt said firing circuit as the relay operates, a norm-ally charged condenser adapted to operate said relay as the condenser is discharged, an anti-countermine device having a pair of normally open contacts adapted to discharge said condenser as the contacts are closed in response to impulses received through the surrounding water, and means including a high resistance winding on said relay for charging said condenser and for maintaining the relay operated while the condenser is recharged by said charging means.

10. In a disarming mechanism for a mine, the combination of, a relay adapted to disarm the mine as the relay operates, a normally charged condenser, a low resistance winding on said relay adapted to be energized by the discharge current of said condenser, an inertia switch adapted to discharge the condenser as an impulse is received through the surrounding water, means for interrupting the discharge of said condenser as the relay operates, means including a high resistance winding on said relay for charging the condenser over a substantially longer period of time than the time of discharge thereof, said high resistance winding being adapted to maintain the relay operated until the condenser is substantially fully charged.

11. In a disarming mechanism for a mine, the combination of a firing circuit, a relay for interrupting said firing circuit when the relay is operated, a normally charged condenser, a normally open discharge path for said condenser, inertia operated means for periodically closing said discharge path in response to vibrations received thereby, and means including a winding on said relay connected to said condenser for charging the condenser therethrough as said discharge path is open thereby to maintain the relay operated while the condenser is being charged.

12. In a disarming mechanism for a mine, the combination of a relay adapted to disarm the mine as the relay operates, a condenser, a first winding on said relay connected to said condenser and adapted to be energized by the discharge current thereof, an inertia actuated switch connected to said first winding and adapted to discharge the condenser in response to an impulse received through the surrounding water, means on said relay for interrupting the discharge of the condenser as the relay operates, and means including a second winding on said relay for charging the condenser, said second winding being adapted to maintain the relay operated until the condenser is substantially fully charged.

References Cited in the file of this patent UNITED STATES PATENTS 1,310,568 Heap et al. July 22, 1919 1,407,653 Hammond Feb. 21, 1922 1,448,976 Palmer Mar. 20, 1923 

